Guo Wei Shu

Effect of Probiotic lactobacillus Strains on Angiotensin I Converting Enzyme Inhibitory Activity from Fermented Goat Milk

Goat milk was fermented by different strains of lactic acid bacterias in anaerobic tube, strains with high angiotensin converting enzyme (ACE) inhibitory activity were screened from 28 probiotic Lactobacillus strains by the criteria of ACE inhibitory activity and pH. The results showed that 20 strains had ACE inhibitory activity and among them the activity of 4 strains were extremely high, they were Lactobacillus reuteri, Lactobacillus bulgaricus, Lactobacillus rhamnosu and Lactobacillus helveticu. In vitro experiments, the ACE inhibitory activity of goat milk fermented by these 4 strains reached 95.92%, 84.61%, 82.79% and 78.57%, respectively. After incubation, pH of them were 6.17, 3.88, 5.24 and 3.71, respectively.

Screening of Nitrogen Sources in the Medium for Streptococcus thermophilus Using Plackett–Burman Design

This study demonstrates that the type of nitrogen sources has an important influence on the growth of Streptococcus thermophilus.at the same time ,viable counts was studied by in the medium containing various nitrogen sources (peptone, yeast extract, meat extract, tryptone，soya peptone and casein hydrolysate). The results indicated that soya peptone was the most efficient nitrogen source and and the influence of different concentrations of soya peptone on growth was determined. The results indicated that viable bacteria were stimulated by the high soya peptone concentration (30g/L).

Effect of Fructo-Oligosaccharide, Isomalto-Oligosaccharide, Inulin and Xylo-Oligosaccharide on Survival of B. Bifidum during Freeze-Drying

Four different prebiotics including fructo-oligosaccharide isomalto-oligosaccharide, inulin and xylo-oligosaccharide were screened for their effects on survival of Bifidobacterium bifidum during freeze-drying. The additions of prebiotics (v/v) were all 4%, 8%, 12%, 16% and 20%. The results showed that prebiotics could act on Bifidobacterium Bifidum. The optimum concentration of fructo-oligosaccharides (FOS) in samples for surival of Bifidobacterium bifidum was 12% and for viable count was 20％. Addition of xylo-oligosaccharides (XOS) played a significant role in promoting cell viablity when it was in low level. The optimum concentration of isomalto-oligosaccharides (IMO) for surival of Bifidobacterium bifidum was 16% and for viable count was 12％, while inulin in samples for surival and viable cell of Bifidobacterium bifidum both was 4％.

Effect of Bile and Nalidixic Acid on Growth of Selected Probiotics

Effect of bile and nalidixic acid on growth of Lactobacillus acidophilus, Bifidobacterium bifidum, Lactobacillus bulgaricus, Lactobacillus casei and Lactobacillus rhamnosus was studied by measuring the optical density at 600nm (OD600) and pH using De Man, Rogosa and Sharpe (MRS ) broth as the control. The addition of bile (%, w/v) was 0.03%, 0.06%, 0.09%, 0.12% and 0.15% and the addition of nalidixic acid (%, w/v) was 0.003%, 0.009%, 0.015%, 0.045% and 0.075%. Results were as follows: addition of bile at the concentration above 0.06% has a significant inhibition on the growth of L. bulgaricus and B. bifidum at incubation 24h. The optimum selective concentration of bile in MRS media was 0.06% for L. bulgaricus and B. bifidum. Addition of nalidixic acid has no effect on the growth of the five selected probiotics at incubation 24h. Addition of nalidixic acid in MRS can not use to realize selective enumeration in yogurt product containing probiotics.

Effect of Five Materials Including Sucrose, Lactose, Skim Milk, Yeast, Vitamin B2 on Survival of Lactobacillus bulgaricus during Freeze-Drying

effect of five materials including sucrose, lactose, skim milk, yeast, vitamin B2 on survival rate of Lactobacillus bulgaricus during freeze-drying was studied by measured survival and the number of viable cells. Designed different concentrations of these different protective agents, respectively, freeze-drying perfectly and then counted the survival ratio of Lactobacillus bulgaricus and the number of viable cells. Results were as follows: addition of skim milk and yeast had significant effects while addition of vitamin B2 had minimal impact on survival rate of Lactobacillus bulgaricus. The optimum concentration of single protective agent of Lactobacillus bulgaricus during freeze-drying was that 25% (W/V) sucrose, 20% (W/V) lactose, 25% (W/V) skim milk, 20% (W/V) yeast and 25% (W/V) vitamin B2, respectively, and survival rate was 24.5%, 35.6%, 64.4%, 62.2%, and 16.3%.

Effect of K2HPO4, KH2PO4, NaHCO3, and Sodium Ascorbate on Survival of Lactobacillus acidophilus during Freeze-Drying

In the present study, the experiments were investigated with the effecting of NaHCO3, KH2PO4, K2HPO4 and Sodium ascorbate on survival of Lactobacillus acidophilus during freeze-drying. Designing different concentrations of protective agents, respectively. The survival ratio of Lactobacillus acidophilus and the number of viable cells will be measured after completing drying. In the process, there were major differences between the different concentrations of protective agents in survival during freeze-drying. As the result, the protective agent was playing a key factor affecting the survival of Lactobacillus acidophilus. At present in the study of the experiments, the highest survival rate was NaHCO3 as the protective agent, and when the protective agent as K2HPO4 the number of viable cells was largest.

Effect of the Extract of Fructus tribuli on Growth of Lactobacillus Acidophilus

Effect of the extract of Fructus tribuli (EFT) on growth of Lactobacillus acidophilus LA04, LA05, LA06 and LA09 was studied by measuring optical density at 600nm (OD600) and pH using MRS culture media as the control. The addition of EFT (v/v) was 1%, 2%, 3%, 4% and 5%. Results were as follows: addition of EFT could promote the growth of Lactobacillus acidophilus LA09, The optimum concentration of EFT in MRS media was 1% at incubation 24h, but addition of EFT on growth of Lactobacillus acidophilus LA04, LA05 and LA06 has no significant effect.

Effect of Sucrose, Lactose, Glucose, Maltose on Survival of Lactobacillus acidophilus during Freeze-Drying

In the present study, the experiments were investigated with effecting of sucrose, lactose, glucose, maltose on survival of Lactobacillus acidophilus during freeze-drying. In order to reach sufficient numbers viable cells, so different concentrations of protective agents were designed in the experiment, which as 3%, 6%, 9%, 12% and 15%, respectively. Measuring the survival ratio of Lactobacillus acidophilus and number of viable cells after completed drying. There were significant differences in survival during freeze-drying. Results showed that the protective agent was a critical factor affecting the survival of Lactobacillus acidophilus. In the experiments, the highest survival rate was soluble starch as the protective agent, and when the protective agent as galactose the number of viable cells was largest.

Effect of Alginate and Cell Suspension on Viable Counts and Efficacy of Entrapment of Encapsulated B. bifidum BB28

This study reports the encapsulation yield (EY) of B. bifidum BB28 encapsulated in different sodium alginate concentrations and in different proportion of BB28 and sodium alginate.It was studied by enumeration of viable cells after depolymerization of the capsules in 9mL trisodium citrate, followed by using MRS agar at 37°C for 48 h. The concentrations of sodium alginate was 1.5%, 2.0%, 2.5% and 3.0%.The proportion of cell suspension and sodium alginate was 1:5,1:10,1:15 and 1:20. Results were as follows: The optimum concentration of sodium alginate concentrations was 2.5% and the optimum proportion of cell suspension and sodium alginate was 1:10.

Effect of Lithium Chloride and Sodium Propionate on Growth of Selected Probiotics

Effect of Lithium Chloride (LiCl) and Sodium Propionate (CH3CH2COONa) on growth of Lactobacillus acidophilus, Bifidobacterium bifidum, Lactobacillus bulgaricus, Lactobacillus casei and Lactobacillus rhamnosus was studied by measuring optical density at 600nm (OD600) and pH using MRS media as the control. The addition of each substance (%, w/v) was 0.025%, 0.05%, 0.1%, 0.2% and 0.3%. Results were as follows: addition of LiCl has the significant inhibition on growth of Lactobacillus acidophilus, Bifidobacterium bifidum and Lactobacillus bulgaricus at incubation 12h. The optimum selective concentration of LiCl in MRS media was 0.1% both for Lactobacillus acidophilus and Lactobacillus bulgaricus. Lactobacillus rhamnosus can tolerate the substances mentioned above. Sodium Propionate has no effect for any of five strains.